In recent years, as a method for forming solder resist layers on printed wiring boards for consumer use and industrial use, a liquid solder resist composition with excellent resolution and dimensional accuracy which can be developed with an alkaline solution has been widely used, instead of a screen printing method, in order to increase the density of wiring on the printed wiring board.
A solder resist layer is sometimes required to have a matte surface, for example, in order to prevent solder bridging caused by solder adhering to the solder resist layer during reflow. Also, a solder resist layer of a printed wiring board mounting a light-emitting diode which has become widely used rapidly in recent years is sometimes required to be black and have a matte surface so that light emitted from the light-emitting diode can be perceived more brightly.
In order to make a surface of the solder resist layer matte, deglossing materials such as fine particles of silica, talc and kaolin are usually added to the solder resist composition (Patent Literature 1).
However, a large amount of the deglossing material is required to achieve a sufficiently matte surface using the deglossing material. Using a large amount of the deglossing material may lead to decrease in electric corrosion resistance of the solder resist layer, decrease in pressure cooker test resistance, and decrease in applicability caused by an increase in a thixotropic property of the solder resist composition.